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Cosmic Rays and Global Warming
Overly Critical Guy writes "The former editor of New Scientist has written an article in the TimesOnline suggesting that cosmic rays may affect global climate. The author criticizes the UN's recent global warming report, noting several underreported trends it doesn't account for, such as increasing sea-ice in the Southern Ocean. He describes an experiment by Henrik Svensmark showing a relation between atmospheric cloudiness and atomic particles coming in from exploded stars. In the basement of the Danish National Space Center in 2005, Svensmark's team showed that electrons from cosmic rays caused cloud condensation. Svensmark's scenario apparently predicts several unexplained temperature trends from the warmer trend of the 20th century to the temporary drop in the 1970s, attributed to changes in the sun's magnetic field affecting the amount of cosmic rays entering the atmosphere."
Before you people start screaming, "what do they expect us to do about cosmic rays??//?/?" Think. This isn't about "debunking" global warming, nor is it about fearmongering about it. It's about building more accurate climate models.
Move along.
http://outcampaign.org/
I have had some classes on this theory at university.
This being a somewhat new theory everything is still quite uncertain how much effect this has on the heating of the earth.
I think the estimates we saw in class a year ago was that this could explain from 10% to maybe 30% of the heating that has happened in the last 30 years.
We don't have measurements of the amount of cosmic radiation from more than something like 30 years so it is hard to go further back to check this theory.
We have CO2 measurements from somewhat longer, but not that much longer, but we have trapped air in the ice cores which give us information almost 100K years back which gives the evidence of CO2 and methane quite strong support.
Cosmic radiation does is not "trapped" anywhere in the geologic layers to my knowledge.
I am no saying Svensmarks theory is wrong, it most likely has an effect, but how big this effect is is very hard to say by now.
Anyhow I think the critique of the UN-report is justified, if this theory is not part of the report. Not taking this theory into account and then saying there is a 90% certainty that humans have caused global warming is not scientific.
... until the experiment has been independently reproduced and there is some more data on whether and how much cosmic radiation affects our climate. So far, there is one paper on this topic (July 2002 issue of Journal of Geophysical Research-Space Physics), and not much else. The experiment is interesting, but rather tenuous in its conclusions. We have a potential mechanism, along with some ways on testing the validity of its predictions. But it's far too early to make this anymore than it is - an idea that needs further exploring.
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Besides, can we link to something more than someone's blog? Here's a link that has a lot more substance and not so much speculation: http://www.sciencedaily.com/releases/2002/07/0207
Those who can, do. Those who can't, sue.
Oh, hell, I'll bite. Venus was always slightly too close to the sun for it's atmospheric water to condense. As a result, no oceans. Without aqueous chemistry, carbon dioxide couldn't turn into carbonates and stayed in the atmosphere. With no water and no life to create an ozone layer, and all it's water stuck in the upper atmosphere, high-energy radiation dissocated the water into hydrogen and oxygen. As the hydrogen went into space, sulfur-containing compounds got oxidized and reacted with the remaining water to make sulfuric acid.
And to make this worthwhile, consider: Earth's ecosystem handles the increasing luminance of the Sun by reducing CO2 concentrations in the atmosphere to reduce the warming effect. In 1 billion years, the concentration will hit zero and then earth fries. Cheers!
http://www.realclimate.org/index.php/archives/2005 /07/the-lure-of-solar-forcing/
4 /12/recent-warming-but-no-trend-in-galactic-cosmic -rays/
6 /10/how-not-to-attribute-climate-change/
http://www.realclimate.org/index.php/archives/200
http://www.realclimate.org/index.php/archives/200
The notion that professional climate scientists have ignored solar forcing in estimating climate sensitivity is 100% false, and by now repeating it is slander.
By no means whatsoever have actual climatologists "forgotten" about the Sun since the earliest days of global warming studies in the 1960's and further. Of course popularizations ignore all the complexities but that's what they do.
The fact remains that by the best known observations and theory there is no way to explain the current observations WITHOUT major to dominant human greenhouse gas forcing.
There is no trend in solar activity observed or predicted which either explains recent past observations or will in any way nullify the clear and significant effect from greenhouse gas forcing. That depends on very predictable laws of physics, not statistical correlations.
And if the Sun does happen to be in an upswing in output, then that will just make the climate change we are causing that much worse. Since the upper extremes of events and risks are the greatest danger, any uncertainty in solar forcing adds to the variance in future forecasts, and not the mean. This means that doing something about the thing we can do something about is ever more urgent.
Just to nitpick, but Galileo Galilei wasn't the first nor the only one to describe heliocentrism - Nicolas Copernic was the forethinker of that system, and Galileo Galilei main discoveries (Saturn's rings, Jupiter's satellites, physics of the pendulum etc.) weren't in the line at his trial. Actually, most of the learned scholars of the time knew for a fact that heliocentrism gave far more accurate mathematicals results to build sailing tables.
Galileo Galilei faced troubles because he wrote that helliocentrism was the physical TRUTH. He would have escaped any trial (and was offered a plea bargain as a matter of fact) had he accepted to write that heliocentrism was a mere hypothesis. But he refused and the rest is history. As to know why he was so stubborn, we now know there was a mix of self-pride, and insurance he received from high profile individuals among the Catholic Church that the Pope was considering adopting a progressive doctrine. That turned out to be deceptive. Basically, he was caught in the middle of a political fight, and sided with the wrong persons.
"....it makes it worth at least looking at his claim"
It has been looked at, and will definitely be "looked at" again iff someone were to come up with a new idea.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
---- No reputible sources are disputing global warming and that humans are the cause.
Uh, think again.
There's a fairly solid consensus that global mean temperatures have gone up about 1.5C in the last hundred and fifty years. There's good proof that humans are putting a significant amount of CO2 into the atmosphere. There's still a lot of room for discussion of how much effect anthropogenic CO2 has on the global mean temperature, though.
Most scientists say, "at least some," but it's hard to pin anyone down to specific numbers. First and foremost, we don't understand the atmosphere well enough to say we know what acounts for natural variation. We know very little about the cloud system, for instance, which has a significant effect on planetary temperature.
If you want to make scientific statements about anthropogenic global warming, you need to be able to answer the following questions:
All measurements have some error, and you can't make meaningful statements about numbers smaller than that error. For most scientific work, an error margin of 5% is considered acceptable. I don't happen to know the error for converting 500-year-old tree ring data to global mean temperature, for instance, but I'd be surprised to find it less than 5%. The same is true for extrapolating global CO2 levels from a microliter of prehistoric gas trapped in an ice core sample.
By the same token, all real data populations have some amount of variation. It might be very small, or it might be very large. Statistically, about 2/3 of a sample falls within one standard deviation (aka: sigma) of the average. That means a variation of less than one sigma is 2/3 likely to be perfectly natural, and only 1/3 likely to be caused by external factors.
And finally we have coefficient of correlation. A CoC of .95 means that when factor A goes up, factor B also goes up 95% of the time. Again, it's scientifically invalid to claim correlations greater than your CoC.
So.. the scientifically valid way to discuss anthropogenic global warming is to say it's X% certain that anthropogenic CO2 accounts for Y degrees of variation in global mean temperature, plus or minus Z degrees of error.
And let's face it, when you carve out a 5% error for basic measurement, figure a standard deviation of between .4C and .75C in the historical temperature data, then factor in a CoC of .8 or so (which is generous for real-world science), there isn't much room left for sweeping pronouncements. If you want to be 95% certain that Y degrees of variation are due to human-produced CO2, you have to set Y somewhere around .1C.
The "we are headed towards an ice age" meme was due to the belief in cyclic weather, basically that the global temperature could be predicted by a Fourier series. You can always fit any measured data to a Fourier series, but here at least some of the coefficients had astronomical explanations.
Global warming was also a concern 30 years ago, as the mechanisms were well known. There were actually people warning about global warming a 100 years ago. However, only recently computers have become fast enough, and measurements accurate enough, that you can actually quantify the risk.
Interestingly enough, cyclic weather has until recently[1] been used to dismiss global warming, claiming that it was not man made but predicted by the coefficients in the Fourier series. Which does apparently conflict with the series predicting an ice age, but not really, as the series consist of overlapping cycles, and you can be on the way up on one of the short cycles, and on the way down one of the longer.
[1] You still see references to it by laypeople on the net, but it is no longer used that way by scientists.
Here's a nice "Cosmic Rays and Climate Change for Dummies" article that has pretty pictures and graphs. At least give it a read before dismissing this. I found it compelling.
http://www.sciencebits.com/ice-ages
more on the climate debate: http://www.sciencebits.com/ClimateDebate/
Shaviv's personal site: http://www.phys.huji.ac.il/~shaviv/
One of the co-authors of that study is a friend of mine. He's bemused by how the press has gotten the data's implications entirely wrong. An average increase in global temperatures results - according to all models - in some local average decreases. The overall patterns change.
Consider the question some must be asking, "Why is there record snow in Mexico, New York now if our winters are warming?" It's because the Great Lakes are warmer than usual because of the unusually warm December and January, so there's more evaporation now that cold winds are finally blowing across, and that becomes snow. Global warming means as a planetary average it snows less (because it's more often rain instead). But locally it may be that Mexico, New York is in for a string of nasty winters.
It's similar effects we're seeing in Antarctica, where local regions have more snow buildup, or more cold, even though on the large scale major ice shelves are breaking off for the first time in tens of thousands of years.
"with their freedom lost all virtue lose" - Milton